High temperature catalytic cracking of gas oils



United States Patent 3,530,064 HIGH TEMPERATURE CATALYTIC CRACKING 0FGAS OILS Nai Yuen Chen, Cherry Hill, and Stanley J. Lucki, Runnemede,N.J., assignors to Mobil Oil Corporation, a corporation of New York NoDrawing. Filed May 29, 1968, Ser. No. 732,893 Int. Cl. Cg 13/00 U.S. Cl.208--113 9 Claims ABSTRACT OF THE DISCLOSURE This invention is concernedwith a process for carrying out the catalytic cracking of hydrocarbons,e.g., gas oils, into products of lower molecular weight wherein the heatnecessary for carrying out the cracking reaction is provided at least inpart by a simultaneous shape selective combustion of lower molecularweight hydrocarbons. Both the cracking reaction and the selectivecombustion reaction take place in the same reactor and are carried outat specific temperatures, space velocities and catalystto-oil (cat-oil)ratios.

BACKGROUND OF THE INVENTION This invention relates to the catalyticconversion of hydrocarbon oils into lower normally liquid and normallygaseous products. More particularly, the present invention is directedtowards a process wherein a high boiling hydrocarbon or hydrocarbonmixture, for example, a petroleum fraction, is subjected to crackingunder very unusual conditions including elevated temperatures whichwould normally be considered to be in the thermal cracking range andwherein heat necessary to effect the cracking reaction is supplied atleast in part by the selective combustion of a portion of the feed and/or reaction products wherein both the cracking and the selectivecombustion reaction take place in the same reactor.

The concept of carrying out a selective combustion reaction in order tosupply at least a portion of the heat necessary for carrying outcracking reaction is not new and is, in fact, taught in the prior artincluding US. 3,136,713. It is to be noted, however, that the heretoforepracticed processes were carried out within the range of conventionaloperating conditions in regard to temperature, space velocity, cat-oilratios, etc. so that although this combination of processes was indeednovel, the operating conditions employed were not that drastic adeparture from conventional technology with regard to either thecracking or combustion reaction.

In copending application Ser. No. 582,584, filed Sept. 28, 1966, nowPat. No. 3,420,770, a novel process is disclosed and claimed involvingthe catalytic cracking of a gas oil to produce gasoline under veryspecific and unusual conditions. In said application, the catalyticcracking is carried out by contacting a feed material with a crackingcatalyst at an average range temperature from a minimum of 1100 F. up toa practical maximum of about 1350 F. and that a minimum space velocity(LHSV) of 32 at 1100 F. to about 1200 at 1300 F. and the maximum cat-oilratio of about 0.1 and, more preferably, 0.01.

As can be readily appreciated, the above-described conditions are adrastic departure from conventionally practiced cracking processes. Ascan be seen from the minimum temperature of 1100 F it can generally bestated that thermal cracking conditions are being employed. It shouldalso be obvious that if, in fact, thermal cracking conditions were beingemployed then, irrespective of what catalyst was being used, no usefulresult would be obtained, i.e., if conditions were used which would inand ice of themselves produce an inordinate amount of gas without anycatalyst then the inclusion of a catalyst at those conditions could notsignificantly improve the product pattern.

Accordingly, the particular space velocities employed are such that thedegree of thermal cracking which can take place does not exceed 10%. Inthis regard, reference is made to FIG. 1, which is a graph representinga plot of the temperature versus the minimum space velocity necessary toinsure no more than 10% thermal conversion. As can be seen, there is adefinite cracking space velocity for each individual temperature Withinthe specified range in order to insure a minimum of thermal conversion.

It should be readily apparent that just as the above set-forthconditions are a drastic departure from conventional cracking conditionsthe same comment can be made with respect to the combustion conditions.Thus, it is not sufiicient merely to employ a catalyst which will beshape selective at conventional conditions, but rather, it is mandatoryto employ a. catalyst which is shape selective at the drastic operatingconditions of this invention.

In addition to the above, when it was attempted to carry out the shapeselective combustion process simultaneously with the cracking process,unexpected results were obtained due to the particular operatingparameters of this invention. As has been described in the prior art, ashape selective combustion rocess is carried out by providing oxidationsurfaces within the internal pore structure of a crystallinealuminosilicate having a pore size such that only a portion of ahydrocarbon stream can enter within the internal pore structure thereofand be combusted. Thus, selective combustion of a combustible mixture ofmolecules of differing molecular shapes is obtained by passing the sametogether with an oxidant at reaction conditions over a crystallinealuminosilicate having rigid three-dimensional networks and crystallinecavities accessible through ports of dimension of about 5 A., saidcavities having included therein a material having catalytic activityfor oxidation whereby at least one species of molecules is selectivelyadmitted because of its molecular shape and acted upon.

As has heretofore been stated, when this process was attempted at theconditions of this invention, very unexpected results were observed.

The first surprising result stemmed from the fact that it wasimmediately observed that there was a critical correlation between theactivity of the cracking catalyst and the ability to carry out theprocess. Contrary to what had heretofore been the case in those hightemperature cracking processes carried out without the introduction ofan oxida'nt, the operable activity range was found to be considerablynarrow In this connection, it was found that the cracking catalystshould have an alpha value no less than about 0.5 or more than aboutfour and, more preferably, an alpha value of about 2.

The alpha value describes the relative activity of a catalyst withrespect to a high activity conventional silica alumina crackingcatalyst. Thus, an alpha value of 2 indicates an activity which is twotimes greater than the conventional reference catalyst.

To determine the alpha value conversion of n-hexane is determined andconverted to a rate constant per unit volume of catalyst and comparedwith that of a silicaalumina catalyst normalized to specific conditions.This method of determining alpha values is more fully described in theJournal of Catalysis, vol. IV, No. 4, August 1965, pp. 527-529.

Thus, the first criticality in the novel process of this invention isthe use of a cracking catalyst having an alpha value of from about 0.5to 4. If materials are employed having an alpha value less than thedesignated limit, in-

sufi'icient activity will exist to carry out the cracking process in adesirable manner. Conversely, if cracking catalysts having alpha valuesgreater than four are employed, the presence of oxygen for reasons notcompletely understood cause a drastic drop in the conversion ability ofsaid catalyst so that it is rendered useless for its intended purpose.

The second criticality of the cracking catalyst employed in thisinvention is that it not have oxidation activity. This requirement isnot too surprising since the purpose of this invention is to limit theoxidation activity to within the pore size of the shape selectivecombustion catalyst. However, it was immediately discovered that underthe operating conditions of this invention certain catalysts were foundto have oxidation activity which did not possess said activity atconventional cracking conditions. Thus, by way of specific example, apreferred cracking catalyst in the majority of conventional catalyticoperations are rare earth aluminosilicates. Such materials cannot beused in the instant process since rare earth aluminosilicates haveoxidation activity under the conditions of this invention.

Representative cracking catalysts which can be used in the instantprocess include certain types of silica-alumina, silica-magnesia,silica-zirconia, zirconia-alumina and, more preferably, crystallinealuminosilicates.

Aluminosilicates which are operable as cracking catalysts in the novelprocess of this invention include a wide variety of compounds, bothnatural and synthetic. Aluminosilicates can be described as athree-dimensional framework of SiO., and A tetrahedra in which thetetrahedra are cross-linked by the sharing of oxygen atoms whereby theratio of total aluminum and silicon atoms to oxygen atoms is 1:2. Thehydrated form aluminosilicates may be represented by the formula:

wherein M represents at least one cation which balances theelectrovalence of the tetrahedra, n represents the valence of thecation, w the moles of SiO and y the moles of H 0. The cation can be anyor more of a number of metal ions depending whether the aluminosilicateis synthesized or occurs naturally. All or a portion of the cationsoriginally associated with the aluminosilicate can be replaced withother cations providing they have no oxidation activity such as hydrogenions, ammonium ions or other metal cations such as, for example,calcium, magnesium, etc. or mixtures thereof. It is to be noted that thereplacing cations or mixtures of cations need only be present in anamount sufficient to give the aluminosilicate composition an alpha valueof from 0.5 to 4.0 and, more preferably, about 2.0.

Aluminosilicates falling within the above formula are well known andinclude synthetized aluminosilicates, natural aluminosilicates, andcertain caustic treated clays.

Among the preferred aluminosilicates one can include zeolites Y, L, X,beta, ZSM-4 and natural materials such as faujasite and mordenite.

If it is desirous to selectively crack straight-chain hydrocarbons froma mixture of the same with other components, zeolites having pore sizesof about 5 A. can be employed. These materials would include zeolites A,D, R, S, T, Z, E, F, Q, B, ZK-4, ZK-S, alpha, ZSM-S, erionite,chabazite, gmelinite, and dachiarite.

The particularly preferred aluminosilicates, however, are those havingpore diameters of at least about 6 A.

It should also be stated that since the alpha value of a particularaluminosilicate increases with decreasing alkali metal ion content thisinvention specifically includes those aluminosilicates which have alphavalues greater than four as a result of replacement of a substantialportion of the alkali metal cations with protons, other metal cations ormixtures thereof provided they are pretreated in order to reduce thealpha to the desired alpha range of 0.5 to 4.

The alpha value of an aluminosilicate can be reduced by many techniquesincluding heat treatment, steaming as well as a combination of boththese techniques. Reduc tion by alpha by heat treatment can beaccomplished by heating the aluminosilicate at temperatures of at leastabout 1500 F. for 1 to 48 hours or longer. Steaming to reduce alphavalues can be carried out at elevated temperatures of 800 F. to 1500 F.and preferably at temperatures of about 1000 F. to 1400 F. The treatmentmay be accomplished in an atmosphere of steam or in an atmosphereconsisting of steam and gas which is substantially inert to thealuminosilicate. A similar treatment can be accomplished at lowertemperatures in elevated pressures, e.g., 350 F. to 700 F. at 10 toabout 200 atmospheres.

It should also be noted that one aspect of this invention resides in thedevelopment of a process which does not require regeneration of acatalyst and therefore other types of aluminosilicates can be used whichhave heretofore been thought to be impractical. Thus, for example, asidefrom the question of activity, a catalyst in a regenerative process mustalso be stable to steam since, in fact, steam is generated in theregenerative operations. In view of this, high sodium contentaluminosilicates, i.e., the sodium faujasites of the X and Y type weregenerally thought to be unsuitable for cracking processes due to theirlack of steam stability. In view of the fact that regeneration is notabsolutely necessary in the instant invention, steam stability is alsonot necessary and high sodium content aluminosilicates can be employed.

As has heretofore been stated, the novel process of this invention iscarried out at temperatures ranging from 1100 to 1350 F. at certaincritical minimum space velocity. It is to be understood that all figuresgiven for space velocity refer to a charge that is 100% hydrocarbon,i.e., no diluent gas is added.

It is specifically pointed out that this invention also includes mixinga hydrocarbon charge with a diluent and passing said mixture over thecatalyst. In situations where a feed is employed which is not 100%hydrocarbon then the space velocities must be chosen so as to insurethat the previously set forth minimums will be applicable to thehydrocarbon portion of the feed. Thus, for example, it has been statedthat for conversion at 1100 F. a minimum space velocity of 32 (LHSV)must be employed in order to insure that no more than 10% thermalcracking will be obtained. If, however, the hydrocarbon feed employedfor conversion at 1100 F. is not all hydrocarbon, but rather, a mixtureof a hydrocarbon with a gas such as steam, flue gas or helium then theminimum space velocity which is employed is merely the space velocitypreviously set forth multiplied by the fraction of the hydrocarbon vaporin the feed so as to give the same vapor contact time. By way ofspecific illustration at 1100 F. a minimum space velocity of 32 isnecessary for a feed which is 100% hydrocarbon. If, however, a feedwhich is employed which is 50 volume percent hydrocarbon and 50 volumepercent helium, steam, flue gas, etc. then the minimum space velocityemployed would merely be /2 of 32 or 16. It should be immediatelyapparent that a 16 space velocity based on a 50-50 mixture ofhydrocarbon and diluent is, in fact, equivalent to a 32 space velocitybased on 100% pure hydrocarbon.

The shape selective combustion catalysts which are operable in the novelprocess of this invention are crystalline aluminosilicates having a poresize of about 5 A. and containing within the intercrystalline spacesthereof an oxidation catalyst.

Examples of suitable crystalline aluminosilicates are to be found amonga number of aluminosilicate materials, and among synthetically preparedcrystalline aluminosilicate materials, and among synthetically preparedcrystalline aluminosilicates which have structure alalogous to andsometimes differing from the materials known to occur naturally.Specific aluminosilicates include charbazite, gmelinite, stilbite,erionite (oifretite), zeolites S, T,

A, ZK-4, ZK- and others. It is to be noted that the term erionite andoffretite will be considered to be identical in meaning as regardsreference to the same or closely equivalent structural mineral form inaccordance with the findings reported in Mineralogical Magazine, vol.33, pp. 66-67, 1962, by H. M. Hey et a1. entitled The Identity ofErionite and Offretite.

It is preferred, however, to employ aluminosilicates having silicon toaluminum atomic ratios of at least 1.8 and in this connectionaluminosilicates such as erionite (offretite), gmelinite, chabazite,etc. are particularly preferred.

Suitable catalytic oxidation surfaces are achieved by deposition withinthe pores of the crystalline aluminosilicate structure of a transitionmetal or compounds thereof capable of catalytically promoting oxidation.Such metals are well known to those in the art and include metals ofatomic numbers 22 to 29, 42 to 47 and 74 to 78 inclusive. Rare earthelements and compounds thereof may also, in some instances, be founduseful. Deposition of the metal Within the crystalline aluminosilicatemay be accomplished by growth of the aluminosilicate crystals in asolution containing an ion of such metal. Thus, suitable crystallineinorganic aluminosilicates containing a transition metal distributedwithin the pores thereof may be produced by effecting the growth ofcrystals of the aluminosilicate from an aqueous mixture containing aWater-soluble ionizable transition metal compound, dehydrating theresulting transition metal containing crystalline product and subjectingthe same to a thermal treatment at an elevated temperaure. The resulingproduct comprises a transition metal dispersed within the pores of thecrystalline aluminosilicate structure characterized by rigidthree-dimensional networks and an effective pore diameter within theapproximate range of about 5 angstroms. An effective crystallinealuminosilicate having a platinum metal distributed within its uniformstructure may be prepared, as described in U.S. 3,373,109 by introducinginto an aqueous reaction solution having a composition, expressed asmixtures of oxides, within the fol lowing ranges SiO /Al O of 0.5 to2.5, Na O/SiO of 0.8 to 3.0 and H O/Na O of 35 to 200, a minorproportion of a water-soluble ionizable platinum metal compound,inducing crystallization of the resulting reaction mixture by subjectingthe same to hydrothermal treat ment, replacing sodium ions of theresulting crystalline product with calcium, dehydrating the material soobtained and thermally treating at a temperature in the approximaterange of 250 F. to 1100 F. to effect at least partial conversion of theplatinum metal-containing ion to a catalytically active state, therebyyielding a resulting composition having platinum metal dispersed withthe pores of a crystalline aluminosilicate characterized by rigidthree'dimensional networks and uniform pores approximately 5 angstromsin diameter.

Aside from introducing the transition metal into the aluminosilicatestructure during the process of crystal growth, such metal may bedeposited within the interior of the crystalline aluminosilicate bybase-exchange of an initially formed alkali metal or alkaline earthmetal aluminosilicate with a solution containing an ion of the desiredmetal. Utilizing this manner of operation, it is generally desirable toremove active catalytic oxidation surfaces attributable to deposition ofthe metal ion on the outer surface of the crystalline aluminosilicatelattice by either of two methods. One method utilizes the effect ofadditional base-exchange treatment with a solution containing an ion ofsize too large to enter the cavities, but effective in exchangingcatalytically active to catalytically inactive ions in all externallocations. Another method relies on contacting the base-exchangedmaterial with a substance capable of poisoning the oxidation active ionsexternally but incapable of reaching and thus effecting the active siteslocated within the cavities. By whatever method may be employed, thecatalytic oxidation surface is caused to be contained only within thecrystalline pore structure and to thereby afford a resulting productcapable of effecting desired selective catalytic combustion.

As has heretofore been pointed out, the novel process of this inventionis carried out by introducing a mixture of hydrocarbons such as apetroleum fraction together with an oxidant into a reactor containing ashape selective combustion catalyst and a cracking catalyst and carryingout the reactions under certain critical conditions. The selectivecombustion catalyst acts upon a portion of the feed and/or reactionproducts from the cracking reaction in order to provide at least aportion of the necessary heat for the cracking reaction. The ratio ofcombustion catalyst to cracking catalyst. is not narrowly critical andweight ratios from about 0.01 to 0.5 are operable with from 0.05 to 02being particularly preferred.

A wide variety of oxidant materials may be employed including oxygen,ozone, sulfur dioxides, sulfur, chlorine, nitrogen, nitrogen oxides, andthe like as Well as mixtures thereof including air. For all practicalpurposes, it is preferred to use air or oxygen.

It has also been found that the amount of oxidant employed has adefinite bearing on the ability to carry out selective combustionreaction. Too much oxidant causes oxidation of desirable portions of thefeed whereas too little does not accomplish the desired purpose. Theexact amount of oxidant employed will obviously vary depending upon thespecific oxidant used. However, sufficient oxidant should be used suchthat to 600 and preferably 300400, B.t.u./lb. of charge stock aregenerated. This is accomplished by burning 0.5 to 3, and preferably 1.52weight percent of the charge.

If oxygen is employed as the oxidant, the amount re quired would be0.017 to 0.115 pounds per pound of charge. Preferably, the amount ofoxygen used ranges from 0.05 to 0.07 pounds per pound of charge. Theamount of oxygen needed can also be expressed in cubic feet instead ofpounds. Thus, the necessary oxygen ranges from 0.22 to 1.8, andpreferably from 0.67 to 0.90 cubic feet per pound of charge.

If air is used as the oxidant, it should be present in amounts rangingfrom approximately 1-10 and preferably 35 cubic feet per pound ofcharge.

Another, though less preferred, embodiment of this invention resides inthe incorporation of the crystalline aluminosilicate cracking catalystin a matrix. Typical matrices and techniques for incorporation aredisclosed in U.S. 3,140,253.

The novel process of this invention is applicable to a wide variety offeed materials including, but not limited to, those feed stockstypically used in commercial refineries. However, maximum benefit isobtained from the instant process if a feed stock is chosen such thatthe proper carbon-hydrogen balance is obtained. By way of considerableoversimplification, it should be realized that a cracking processinvolves the redistribution and rearrangement of carbon and hydrogen,and in order to produce desired products, there must be a sufficientamount of carbon and hydrogen originally present in the feed.

If a feed stock is chosen which is hydrogen deficient the A mixture ofhelium and a Light East Texas Gas Oil (LETGO) having a hydrogen contentof 13.05 percent by weight was preheated to 900 F. and thereaftercharged into a reactor filled with quartz chips and maintained atelevated temperatures in order to effect conversion of the gas oil.After five minutes, a material balance of the product stream was made,and the results of the analysis as well as the specific experimentalconditions are shown in the following table.

TABLE Example I II III Catalyst None None N one Charge rates per minute:

gas oil, g 0. 423 0. 423 0. 423 He, cc 420 420 420 Average temperature,1,062 1, 255 1, 150 Vapor contact time, sec.-. 0. 008 0.008 0. 023Conversion, wt. percent 2. 1 2. 9 2. 3

From the above three examples, it can be seen that even at high reactiontemperatures little conversion was obtained at the high space velocitiesemployed. In these experiments the effect of thermal cracking has beenminimized due to the novel combination of high temperature and highspace velocities.

In all the examples which follow, unless otherwise indicated, prior toeach individual catalyst being evaluated for cracking, it was calcinedat the reaction temperature for 30 minutes with a 50/10 cc. per minuteflow rate of a helium/oxygen mixture after which the reaction was purgedwith helium at a flow rate of 50 cc. per minute for 20 minutes.

EXAMPLE 4 This example will illustrate that a rare earth aluminosilicatecannot be used as the cracking catalyst in the instant process, althoughsaid materials are excellent cracking catalysts at these conditions inthe absence of an oxidant.

A catalyst mixture consisting of seven parts by volume of a steamed rareearth aluminosilicate having an alpha value of 2.8 and 3 parts by volumeof a shape selective combustion catalyst comprising platinum containingzeolite T was tested for the cracking of a hydrotreated Beaumont chargestock according to the following procedure:

A hydrogen deficient Beaumont charge stock having the followingcomposition:

13.6 weight percent Light Mid-Continent Gas Oil; 9.7 weight precentLight Coker Gas Oil;

37.2 Heavy Virgin Mid-Continent Gas Oil;

11.5 weight percent Heavy Coker Gas Oil;

28 weight percent of an overhead of a 1:1 ratio of T.C.C.; Heavy cyclestock and furfural extract.

was contacted with hydrogen under hydrogenation conditions until thetotal weight percent of hydrogen in the With oxygen Without oxygen Time,hours 4.6 2. 5

Conversion, wt. percent 3. 4 42. Product, selectivity, we. perce C plusgasoline... 50. 0 73. 9

As can be seen, the presence of oxygen drastically reduced theeffectiveness of the rare earth aluminosilicate both in conversion andin product selectivity for gasoline.

Examples 5-8 illustrate the effect of the oxygen to hydrocarbon ratio onthe oxidation activity of the shape selective catalysts at the reactionconditions of this invention. The mixture used in the examples containshelium and hydrocarbons in the following proportions:

Percent Propylene 0.24 Isobutane 0.24 Isohexane 0.06

EXAMPLE 5 A calcium aluminosilicate identified as zeolite 5A containing0.4 weight percent platinum was contacted with the mixture of helium andhydrocarbons at an apparent contact time of 0.0001 second and at atemperature of 1300 F. The following table illustrates the results ofthis experiment at two ditferent concentrations of oxygen. Theexpression O HC of .8 signifies of the theoretical amount of oxygennecessary to convert all the carbon atoms to CO and all the hydrogenatoms to water. A O /HC of 0.4 signifies 40% of the theoretical amountof oxygen necessary to convert all the carbon atoms to CO and all thehydrogen atoms to water.

TABLE O /HC of 0.8: Wt. percent Propylene 83 Isobutane 19 Isohexane 19 O/HC of 0.4:

Propylene 43 Isobutane About 1 Isohexane 1 EXAMPLE 6 The above examplewas repeated with the exception that the contact time was 0.00017second.

TABLE O /HC of 0.8: Wt. percent Propylene 100 Isobutane 37 Isohexane 61O /HC of 0.4:

Propylene Isobutane 5 Isohexane 14 EXAMPLE 7 A synthetic crystallinealuminosilicate identified as zeolite T containing 0.2 weight percentplatinum was tested in the identical manner as Example 5 at an apparentcontact time of 0.0021 second with the following result.

TABLE O /HC of 0.8: Wt. percent Propylene Isobutane 67 Isohexane 88 O/HC of 0.4:

Propylene 98 Isobutane 7 Isohexane 21 EXAMPLE 8 An ammonium exchangezeolite identified as erionite and containing 3.5 weight percent nickelwas tested in the same manner as Example 5 at an apparent contact timeof 0.00048 second. The results at two difierent levels of oxidantconcentration are as follows:

TABLE O /HC of 0.8: Wt. percent Propylene 68 Isobutane 26 Isohexane 39 9O /HC of 0.4:

Propylene 50 Isobutane 9 Isohexane 7 Examples to 8 illustrate thatexcellent results are obtained at lower concentration of oxidant whereasat the higher concentration of oxidant unselective oxidation of the feedtakes place.

EXAMPLE 9 A catalyst mixture was prepared by mixing together (1) Sevenvolumes of a synthetic crystalline aluminosilicate cracking catalysthaving an alpha rating of about 1.3 and prepared by treating syntheticfaujasite of the Y type as follows:

164 grams of zeolite Y was oven-dried at 230 F. and thereafter steamedat 1000 F. for 90 minutes with 4400 cubic centimeters of steam perminute. The steamed material was then base exchanged with a 1 normalsolution of ammonium chloride overnight at room temperature. Thealuminosilicate was then filtered, washed and dried overnight at 230 F.and refluxed for 90 minutes at 216 F. with 2070 cubic centimeters of a0.25 normal solution of ethylenediaminetetracetic acid which had its pHadjusted to about .1 with sodium hydroxide. The aluminosilicate was thenfiltered and washed with 2070 cubic centimeters of water and dried at230 F. overnight.

5 grams of the above aluminosilicate were mixed with 50 cc. of a 0.5normal solution of sodium acetate for 1 /2 hours at room temperature.This procedure was repeated for a total of three times. The mixture wasthen filtered and washed three times with 50 cc. of distilled water. Thecatalyst was then dried for 64 hours at 100 C. to yield a catalysthaving a sodium content of 2.96 weight percent; and

(2) Three volumes of a shape selective combustion catalyst prepared inthe following manner:

7.87 grams of sodium aluminate, 17.6 grams of sodium hydroxide, 9.8grams of potassium hydroxide in 122 ml. of water and 178 grams ofcolloidal silica were mixed together for minutes to form a thick gel. Tothis mixture was added 25 cc. of platinum amine chloride solution withstirring for five minutes. The mixture was then placed in a steam bathand heated at 190 F. overnight without steaming. This preparationyielded a catalyst identified as zeolite T containing 0.5 weight percentplatinum within its internal pores.

The above catalyst mixture was placed in a reactor and charged with a 3to 1 mol ratio mixture of helium and the hydrotreated Beaumont chargestock of Example 4 at a temperature of from about 1150 to 1200 R, anLHSV of 420 based on the cracking catalyst. Oxygen was also charged inan amount of 0.03 lbs/lb. of charge. The results of the above experimentshowed that under these drastic conditions, conversion of the gas oilwas maintained at above 30% for 4.5 hours and above for 6.6 hours. Thiscatalyst treated 1900 pounds of charge stock per pound of catalyst.

EXAMPLE 10 A catalyst mixture was prepared by mixing together (1) Sevenvolumes of a crystalline aluminosilicate prepared according to thefollowing manner:

20 grams of a crystalline aluminosilicate identified as zeolite Y wereplaced in a Soxhlet reactor with 7.35 grams of ethylenediaminetetraceticand the mixture refluxed overnight. The product was then filtered andwashed to yield a catalyst having an alpha value of about 0.6; and

(2) Three volumes of the shape-selective catalyst employed in Example 9.

This mixture of catalysts was then placed in a reactor and tested forthe conversion of a mixture of helium and the hydrotreated Beaumontcharge stock of Example 4 in a molar ratio of 3 to 1 at a temperature of1150" to 1200 F., and at 420 LHSV based on the cracking catalyst oxygenwas added at 0.3 lbs./ lb. of charge.

After a period of 8 hours, it was calculated that under these conditionsone pound of catalyst could have treated 1500 pounds of charge stock.

It is to be understood that the above description is merely illustrativeof the preferred embodiments of the invention and is not intended thatit be limited thereto except as necessitated by the appended claims.

What is claimed is:

1. A method of internally heating a catalytic cracking zone containing acombustible fuel component wherein a fluid hydrocarbon charge undergoescracking in the presence of a solid porous cracking catalystcharacterized by having an alpha value of from about 0.5 to about 4 andbeing substantially free of oxidation activity which comprisesintroducing into said zone together with said charge an oxidant and inadmixture with said cracking catalyst a crystalline aluminosilicatehaving rigid three-dimensional networks hearing within the interiorthereof catalytic oxidation surfaces and having a pore size of about 5A. which are sufliciently large to admit said oxidant and said fuelcomponent but sufliciently small to exclude at least a portion of thehydrocarbon charge, initiating combustion of said fuel component incontact with said catalytic oxidation surfaces whereby the temperatureof said reaction zone ranges from about 1100 F. to about 1350 F. so asto effect cracking of said hydrocarbon charge to normally liquidhydrocarbons lighter than said charge and a gaseous product, utilizingsaid gaseous product as the aforementioned fuel component, the reactionbeing carried out at space velocities ranging from 32 to 1200 LHSV andat catalyst-to-oil ratios, based on the cracking catalyst, no higherthan 0.1.

2. The process of claim 1 wherein the cracking catalyst is a crystallinealuminosilicate having a pore size greater than 6 A.

3. The process of claim 2 wherein the cracking cata lyst has an alphavalue of about 2.0.

4. The process of claim 2 wherein the shape selective combustioncatalyst has a silicon to aluminum atomic ratio of at least 1.8.

5. The process of claim 2 wherein the gaseous oxidant is oxygen.

6. The process of claim 2 wherein the gaseous oxidant is air.

7. A method for internally heating a catalytic cracking zone containinga combustible fuel component wherein a fluid hydrocarbon chargeundergoes cracking in the presence of a faujasite characterized by analpha value of from 0.5 to 4 and substantially free of oxidationactivity which comprises introducing air into said zone together withsaid charge and in admixture with said faujasite, a crystallinealuminosilicate having a pore size of about 5 A. and bearing within theinterior thereof catalytic oxidation surfaces, initiating combustion ofsaid fuel component in contact with said catalytic oxidation surfaceswhereby the temperature of said reaction zone ranges from about 1100 toabout 1300" P. so as to effect cracking of said hydrocarbon charge tonormally liquid hydrocarbons lighter than said charge in a. gaseousproduct, utilizing said gaseous product as the aforementioned fuelcomponent, said reaction being carried out at a space velocity of fromabout 32 to about 1200 LHSV and a catalyst-to-oil ratio no higher than0.1, based on the faujasite.

8. The process of claim 1 wherein the shape selective combustioncatalyst having a pore size of about 5 A. is erionite.

1 1 9. The process of claim 1 wherein the shape selective combustioncatalyst having a pore size of about 5 A. is zeolite T.

References Cited UNITED STATES PATENTS 3,033,778 5/1962 Friletta 208-12012 3,136,713 6/1964 Miale et a1 208-113 3,357,916 12/1967 Smith 208120DELBERT E. GANTZ, Primary Examiner 5 A. 'RIMENS, Assistant Examiner U.S.Cl. X.R. 208-120 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,53 Dated September 22, 1970 Inventor) NAI YUEN CHEN andSTANLEY J. LUCKI It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 3, line 35, that portion of the formula reading "M OAl O shouldread --M O:Al O

15 5 Column L, line 3, "by" should read --of--. Column 5, line 31,"resuling" should read --resulting-. Column 7, line 2?, "reaction"should read --reactor--. Column 7, line 68, "we" should read wt.

(line 3 of chart) SIGNED ANu REALEI [Elm I Attest:

m E. p m.

L Um Oomiasioncr of Patent. J

